1 /* 2 * This code was written by Rich Felker in 2010; no copyright is claimed. 3 * This code is in the public domain. Attribution is appreciated but 4 * unnecessary. 5 */ 6 7 #include <wchar.h> 8 9 size_t mbsnrtowcs(wchar_t *restrict wcs, const char **restrict src, size_t n, size_t wn, mbstate_t *restrict st) 10 { 11 size_t l, cnt=0, n2; 12 wchar_t *ws, wbuf[256]; 13 const char *s = *src; 14 15 if (!wcs) ws = wbuf, wn = sizeof wbuf / sizeof *wbuf; 16 else ws = wcs; 17 18 /* making sure output buffer size is at most n/4 will ensure 19 * that mbsrtowcs never reads more than n input bytes. thus 20 * we can use mbsrtowcs as long as it's practical.. */ 21 22 while ( s && wn && ( (n2=n/4)>=wn || n2>32 ) ) { 23 if (n2>=wn) n2=wn; 24 n -= n2; 25 l = mbsrtowcs(ws, &s, n2, st); 26 if (!(l+1)) { 27 cnt = l; 28 wn = 0; 29 break; 30 } 31 if (ws != wbuf) { 32 ws += l; 33 wn -= l; 34 } 35 cnt += l; 36 } 37 if (s) while (wn && n) { 38 l = mbrtowc(ws, s, n, st); 39 if (l+2<=2) { 40 if (!(l+1)) { 41 cnt = l; 42 break; 43 } 44 if (!l) { 45 s = 0; 46 break; 47 } 48 /* have to roll back partial character */ 49 *(unsigned *)st = 0; 50 break; 51 } 52 s += l; n -= l; 53 /* safe - this loop runs fewer than sizeof(wbuf)/8 times */ 54 ws++; wn--; 55 cnt++; 56 } 57 if (wcs) *src = s; 58 return cnt; 59 } 60
